The present invention relates to shampoo compositions, and more particularly to shampoo compositions containing non-volatile silicone materials which condition the hair leaving it softer and more manageable.
When washing the hair with conventional shampoo compositions, the natural oils are removed together with the dirt and unwanted oils. When too much of the natural oil is removed, for example by especially frequent washing, the hair becomes less easy to comb or style, and subject to static build-up causing "flyaway".
Hair conditioners have been developed to try to restore the condition of the hair. These compositions are normally applied to the hair after shampooing, left on the hair for a period of time and rinsed off. This process is time consuming and expensive since two separate products are needed.
Conditioning shampoos containing cationic conditioning agents have been disclosed for example in EP 18 717 (Unilever). These cationic agents confer some conditioning benefit on the hair, but are often thought to leave a residue on the hair, which may cause dulling on dry hair.
Silicone oils are known to be conditioning agents and their use in conditioning shampoos has been proposed for example in EP 74 264 (Unilever) and EP 77 920 (Kao). However, it has been found that care is needed when formulating silicone containing shampoos as the compositions are often unstable and the silicone oil tends to separate out.
EP 181 773 (Procter & Gamble) attempts to solve the problem of stability by incorporating e.g. ethylene glycol mono or di-stearates into the shampoo composition to act as a suspending agent for the silicone oil. In order to act as a suspending agent, crystals of the ethylene glycol stearate have to form in the surfactant, and this is achieved by heating the mixture to the point at which the ethylene glycol stearate dissolves in the surfactant. This process is relatively expensive as well as time consuming, since the mixture must be allowed to cool before further processing can take place.
We have found that suspension of silicone oils in a shampoo composition can be achieved more efficiently and at a lower cost by use of certain specific suspension agents.
The invention accordingly provides an aqueous shampoo composition comprising in addition to water
(a) from 2 to 40% by weight of surfactant chosen from anionic, nonionic or amphoteric surfactant, or mixtures thereof; PA0 (b) from 0.01 to 10% by weight of insoluble, non-volatile silicone; PA0 (c) from 0.5 to 5% by weight of suspending agent chosen from polyethylene glycol mono- or diesters of C.sub.16-22 fatty acid having from 2 to 7 ethylene oxide groups.